Brief periods of exercise are generally good and most physicians recommend it but prolonged exercise can be dangerous.
Studies indicate that exercise over long periods can result in an increase in the mother’s core temperature (hyperthermia). This increase may also raise the core temperature of the fetus, which may result in a congenital malformation. Fortunately, exercise of 15 minutes or less is not likely to raise the mother’s core temperature enough to cause problems to the fetus. If the mother exercises longer than 15 minutes, she must monitor her temperature; it should not go higher than 100.4 degrees Fahrenheit.
Of additional interest: Adequate daily physical activity can be helpful in maintaining a healthy weight for pregnant women. You may be interested to know that a pair of researchers has identified cesarean section as an obesity-associated complication. Obese women are three to four times as likely as thinner women to undergo a cesarean section, according to the report in the January issue of Obstetrics and Gynecology. Paul Kaiser and co-author Russell Kirby, from the Milwaukee Clinical Campus of University of Wisconsin looked at nearly 1900 patients at a nurse-midwifery practice in Milwaukee. Of this group, there were about 100 cesarean births. Nearly 8% of obese women underwent a cesarean delivery compared with 4%of average-weight women, the researchers note. Kaiser and Kirby also found that women who gained excess weight in pregnancy doubled their risk of cesarean section. Of the women who were overweight before they got pregnant, 70% gained more than the recommended amount of weight during their pregnancies.